A high-performance knitting machine in which a needle bed, typically the needle cylinder, has latch needles and knock-over bits thereon is described in German Patent Disclosure Document DE-OS No. 31 08 041. The knock-over bits are moved outwardly during the pull-in movement or retraction movement of the needles in order to facilitate sinking of the loop and thereby improving loop formation, while, additionally, improving the operation and output of the machine. The knock-over bits which, at the same time, function as sinker jacks, must carry out a composite movement. In addition to the projection and retraction movement, the knock-over bit-sinker jack elements must carry out a movement which, in the plane of projection and retraction, extends transversely to the longitudinal extent of the needles, so that the sinker nose or projection thereof can hold the knit goods during projection of the needles, while releasing the loops during sinking of the loop. The sinker nose customarily defines a sinker notch which merges into the sinker edge of the element in the head region thereof.
The longitudinal movement of the sinker jack-knock-over bit elements is customarily controlled by a jack cam which is in engagement with a suitable butt located at an end portion of the longitudinal shaft of the bit, and positioned between the respective needles. The butts are in engagement with the cam race which, in well known manner, causes relative movement with respect to the needle bed. In a circular knitting machine, this may be, for example, the needle cylinder. The transverse movement or rocking movement, can be controlled by forming a circumferentially inclined camming surface on the needle cylinder in the vicinity of the edge of the needle cylinder, the circumferential camming surface forming a bit projection cam. As the bits are projected, a control cam element on the shaft thereof will engage the cam. Consequently, the bits will be tipped or rocked outwardly as they are further projected in their projecting movement by the cam race. The entire shaft, then, will operate in the form of a single-arm lever, restrained in position by the projecting-retracting cam race and tipping about the circumferential cam on the edge of the needle cylinder. The head of the knock-over bit, located on a shaft portion beyond the circumferential cam race, will thereby be rocked in a plane parallel to the width of the knock-over bit which, normally, is in the shape of a longitudinal strip of metal.
Knitting machines of this type are particularly simple to build, and the control of the knock-over bit-jack sinker elements is simple. Yet, the inclined circumferential camming surface must be carefully made and hardened, in order to prevent excessive wear and tear thereon, and further to permit ready exchangeability of the elements of the knitting machine subject to breakage, deformation, or other malfunction. It is also difficult to control the transverse movement of the bits independently of the longitudinal movement thereof. It would be desirable to effect such control for precise control of loop formation, and do so without introducing additional complexity to the machines.
Circular knitting machines have been proposed in which transverse movement of the knock-over bits can be controlled independently of the longitudinal movement--see U.S. Pat. No. 2,090,500, and German Patent Disclosure Document DE-OS No. 20 25 144. The circular knitting machine shown in the U.S. Pat. No. 2,090,500 utilizes rocking-type knock-over bit-jack sinker combinations positioned in the dial, whereas the needles are located in the cylinder, the knock-over bits being positioned between the respective needles. Longitudinal movement of the bits is controlled by a dial cam race, positioned over the needle cylinder via positioning jacks; the rocking movement or transverse movement requires a separate cam race for the bits positioned on the dial. The manufacturing cost for such a machine is considerable and is in excess of that economically feasible for a single-bed circular knitting machine.
The circular knitting machine described in the referenced German Patent Disclosure Document DE-OS No. 20 25 144 requires special shaping and bearing arrangements for the knock-over bit-jack sinker elements and, additionally, complex camming control curves which are difficult to manufacture located on a needle cylinder, to form the bit control cam races or elements.